In patients with kidney transplantation, generally, chronic rejection is diagnosed by renal biopsy. However, the patients are suffered from periodic renal biopsy, which may deteriorate the renal function concomitantly. Furthermore, such chronic rejection proceeds slowly, with the resultant poor subjective symptoms, and therefore, most patients reject painful renal biopsy.
Meanwhile, renal function tests giving the indicators of the progress of chronic rejection have been practiced because renal function is damaged due to chronic rejection. At the tests, urine protein, urine albumin, and urine transferrin etc. have been assayed as the indicators of the acceleration of protein permeability, reflecting glomerular abnormality, and blood creatine, blood urea nitrogen (BUN), blood .beta..sub.2 -microglobulin and blood .alpha..sub.1 -microglobulin have been assayed as the indicators of the decrease of glomerular filtration rate (GFR). However, the change of the test values in the progress of chronic rejection is mild, and when abnormal test values are detected, the chronic rejection has already exerted symptoms at the end stage. So far, not any test method has been known, which can enable early detection of chronic rejection by assaying endogenous substances in body fluids such as urine and blood. Since no such simple test method is currently present, patients with poor subjective symptoms of chronic rejection fall into the end stage, with no appropriate treatment, so that the patients frequently lose their renal function.
It is an object of the present invention to provide simple methods capable of detecting chronic rejection at its early stage after organ transplantation.